Electroluminescent devices and displays with integrally fabricated address and logic devices fabricated by printing or weaving

ABSTRACT

Improved electroluminescent and photonic devices with integrated logic and control circuits are disclosed. Low mobility, contact barrier, space charge limitation and carrier balancing are provided solutions that increase efficiency, reliability and longevity of the devices. Device power loss and power requirements are reduced. True-ohmic contact materials allow a gate-controlled, light emitting organic triode MESFET configuration that eliminates commonly used ITO thereby increasing luminous output, and providing ease of address and control by integrally fabricated complementary MESFET address and control circuitry. The devices can be fabricated by printing or by weaving appropriate materials, and can be configured as color displays.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. non-provisional applicationSer. No. 09/823,269, filed Mar. 30, 2001 now U.S. Pat. No. 6,873,098entitled “Electroluminescent devices and displays with integrallyfabricated address and logic devices fabricated by printing or weaving”,which is a continuation-in-part of U.S. patent application Ser. No.09/218,233, filed Dec. 22, 1998, now U.S. Pat. No. 6,229,259 each ofwhich are hereby incorporated by reference in their entirety.

FIELD OF THE INVENTION

This invention is directed toward triode electroluminescent devices,structures and materials comprising carrier injection contacts which areapplied to improve or replace organic light emitting diode (LED)fabrication processes and contact materials. More particularly, theinvention is directed toward solution deposited and ink-jet printedmetal-organic and organic-polymer semiconductors and electroluminescentsemiconductors which are used to form panel displays and other photonicdevices and products. Alternately, the devices can be fabricated byweaving constituent materials.

BACKGROUND OF THE INVENTION

U.S. Pat. Nos. 5,656,883 and 4,663,559, both to Alton O. Christensen,Sr. (Christensen) disclose true-ohmic contact structures for injectingcharge into a vacuum interface, namely, field emission. U.S. Pat. No.5,977,718, U.S. patent application Ser. No. 08/281,912 and U.S. patentapplication Ser. No. 09/218,233, all to Christensen, disclose othermaterials of a true-ohmic contact interface to inorganic, organic andpolymer devices. More specifically, U.S. patent application Ser. No.09/218,233 discloses woven polymer semiconductors and electroluminescentfibers comprising pixel components and control circuitry. Furthermore,U.S. patent application Ser. No. 08/281,912 discloses true-ohmiccontacts to inorganic and metal-organic materials.

The status of the prior art in electroluminescent (EL) polymer devicedesign is well documented by the review article by R. H. Friend, et al.,in “Electroluminescence in Conjugated Polymers,” NATURE, Vol. 397, Jan.14, 1999, p 121. This article, hereafter referred to as “Friend”, islimited to conjugate polymer light emitting diode devices (LED's) havingindium-tin oxide (ITO) as the hole-injecting contact. The reference iscited not only as background of the prior art, but also because specificneeds for improvement in the prior art are discussed. These aresummarized as follows by topic with applicable page, column and initialline number:

1. Low barrier contacts: (page 124, col. 2, line 17) Friend states thatboth hole-injecting and electron-injecting electrodes with relativelylow barriers for charge injections are required so that high currentdensities and concomitant light emission are produced at low voltages.

2. Low mobility: (page 124, col. 2, line 12) Friend states that mobilityis field (energy) dependent.

3. Space charge limitation: (page 124, col. 2, line 1) Friend statesthat current flow in LED's is not limited by injection, but bulk limitedby build up of space charge from low carrier mobility.

4. Current balancing: (page 125, col. 1, line 5) Friend states thatinjection and transport of holes into the bulk of the polymer must bematched by injection and transport of electrons from the oppositeelectrode, and that the control of injection rates (by introducingheterojunctions) has been shown to be effective for obtaining chargebalance.

5. Reduced radiative emission: (page 126, col. 1, line 25) Friend statesthat in device structures of the type discussed here, the presence of ametallic cathode (ITO) provides a mirror thereby reducing the emissionrates.

6. Interchain interaction reduces radiative emission: (page 125, col. 2,line 38 and page 126, col. 1, line 3) Friend states that interchaininteractions produce lower energy excited states not strongly radiative,

7. Need economic integrated pixel control circuitry; (Page 127, col. 1)Friend discusses needs for economically efficient means for producingintegrated pixel control circuitry.

Improvements in these areas will be set forth in subsequent sections ofthis disclosure.

SUMMARY OF THE INVENTION

This disclosure is directed toward improvements in efficiency andoperation of solution deposited and ink-jet printed electroluminescentand photonic devices. These devices can also be fabricated by weaving.Prior art interface low mobility, contact barrier, space chargelimitation and carrier balancing are incorporated. These properties tendto increase efficiency, increase reliability and longevity, reduce apower loss, and reduce power requirement of LED devices. Contactmaterials and a light emitting triode configuration are disclosed thateliminates ITO commonly used in prior art devices. This increasesluminous output, and provides ease of address and control by the use ofintegrally fabricated triode address and control circuitry.

As mentioned above, U.S. Pat. Nos. 4,663,559, and 5,656,883 toChristensen disclose a true-ohmic, no-barrier, non-tunneling, injectingcontact between the low work function metal Cr.sub.3Si and SiO.sub.2(silica) as a n-type semiconductor, co-deposited as a cermet. Contactequilibrium accumulates the silica conduction band with electrons. Theseelectrons are less than 1 electron volt (eV), and typically 0.6 eV fromvacuum level. In U.S. patent application Ser. No. 09/218,233, this sameinterface physics is extended to an injecting, non-tunneling ohmiccontact obtained between the cermet and n-type polymer semiconductorsand electroluminescent (EL) material. This type of contact, atequilibrium, injects electrons into the polymer semiconductor conductionband, prohibits tunneling, and permits only minimal hole conduction. Theohmic contact to EL semiconducting polymers allows a third, gateterminal to be effective in controlling avalanche in the semiconductor.The cermet contact to EL polymer blocks hole current flow, increases ELcarrier recombination, and improves efficiency and luminous output overprior art tunneling EL devices. Furthermore, U.S. patent applicationSer. No. 09/218,233 discloses woven polymer semiconductors andelectroluminescent fibers comprising pixel components and controlcircuitry. The apparatus and methods can be used to produce a flexible,cloth-like flat screen display.

U.S. Pat. Nos. 5,656,883 and 4,663,459, U.S. patent application Ser. No.08/281,912 and U.S. patent application Ser. No. 09/218,233 are herebyentered into this disclosure by reference. This disclosure sets forthapparatus and methods for improving triode electroluminescent devices,structures and materials comprising carrier injection contacts, whichare now applied to improve or replace organic LED fabrication processesand contact materials.

The improved apparatus and methods are particularly applicable tosolution deposited and ink-jet printed metal-organic and organic/polymersemiconductors and electroluminescent semiconductors that form devices,displays and other photonic devices and products. Elements are printedin pattern and in a sequence required to produce cooperative elements ofthe devices

An alternate means of fabrication is the weaving process disclosed inU.S. patent application Ser. No. 09/218,233 and previously entered intothis disclosure by reference. A class of such polymers, consisting ofmicrofibers of micron and sub-micron dimension, is woven into silk-likefabrics. The ability of certain co-polymers to emit light has been knownfor less than two decades. Selected conjugate or ladder-type polymersmay have dielectric, resistive, thermal conductivity, n or p typeconductivity and EL properties

The above references entered by reference teach the principles,materials and means for providing true solid/solid interfaceMott-Gurney, no-barrier, true-ohmic contact to n-type semiconductinginorganic and metal-organic compounds, polymers and co-polymers of bandgaps greater than 2 eV used in electronic circuitry, EL and otherphotonic devices. In summary, the teachings and effects are as follows:

1. When contact is made between an n-type semiconductor and a conductorwhose work function Φ_(m) is less than half of (E_(g)/2χ) where E_(g) isthe semiconductor band gap and χ is the electron affinity, then chargeexchange occurs to obtain equilibrium;

2. in the charge exchange, interface traps are filled and the conductionband of the semiconductor is accumulated with electrons;

3. the greater the positive difference between (E_(g)/2−χ−Φ_(m)) andwork function Φ_(m) the greater charge exchange occurs to achieveequilibrium, filling some bulk traps as well; and

4. the net effect is to increase conductivity, electron mobility andreduce space charge.

These principles, materials, and methods are utilized in the presentinvention. Two high conductivity contacting metals, each capable ofproducing true ohmic contact to semiconductor and EL semiconductors ofband gap greater than 1.5 eV, are employed in the apparatus of thepresent invention. These contact materials are CuCa₂ with a workfunction of about 1.6 eV, and Al₂Li₃ with a work function of about 1 eV.CuCa₂ prevents diffusion and electromigration of Cu, has a relativelyhigh conductivity and adapts readily into the prior art LED processingenvironment requiring background pressure of 10⁻⁶ mbar of O₂ (seeFriend, page 123, col. 2, line 34). When fabricated by printing or otherdeposition means, Al₂Li₃ requires a suitably positive pressure of argon(Ar) both during the solution formation and the deposition. Polymers andco-polymers of electroluminescent devices and both CuCa₂ and Al₂Li₃require protective coating, or overall encapsulation, to preventoxidation. Either CuCa₂ contacts or preferably Al₂Li₃ contacts improveLED operation. Both CuCa₂ and Al₂Li₃ alloy with polymer and co-polymersemiconductors and electroluminescent devices at about 30° centigrade.

Disclosed are method and means of eliminating the barrier and reducedradiative emission of prior art ITO cathode by transforming the LEDstructure into a triode gate controlled metal semiconductor field effecttransistor (MESFET)-like structure having a surrounding gate thatcontrols carrier energy and carrier balance. The true-ohmic contactsdisclosed inject carriers and fill interface and bulk traps. Thisincreases carrier mobility by a factor approaching 10⁴ and space-chargedistance by a significant factor, allowing more concentration ofradiative chain emission and thus more radiated output. The pixel MESFEToperates in a short-channel, normally “off”, gate-controlled high-energymode, up to and including avalanche, thereby increasing radiative outputand decreasing power required. Basis information on MESFET operation isincluded in the literature. The MESFET field has polymer-chain fieldorientation, rather than LED cross-chain field, thereby furtherimproving efficiency and radiative emission by lowering non-radiativeinterchain reaction. The MESFET's surrounding gate enhances carrierbalancing. Carrier balancing may be “tuned” for a particular polymer orcopolymer by the positioning of the gate relative to the cathode. TheMESFET gate electrode provides reduced cross talk and ease of pixeladdressing as compared to LED's.

Since the MESFET device comprises organic elements, it will sometimes bereferred to as an “organic” MESFET or “OMESFET”.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features, advantages andobjects the present invention are obtained and can be understood indetail, more particular description of the invention, briefly summarizedabove, may be had by reference to the embodiments thereof which areillustrated in the appended drawings:

FIG. 1 is a partial cross section of a prior art electroluminescentdiode;

FIG. 2 is a partial cross section of an improve version of the prior artdiode shown in FIG. 1;

FIG. 3 is a cross section schematic of the preferred OMESFET used inpixels and control circuitry;

FIG. 4 is a partial planar view schematic of the preferred OMESFET usedin pixels and control circuitry shown in FIG. 3;

FIG. 5 is a partial cross section of an OMESFET suitable for fabricationusing printing methods;

FIG. 6 is a partial planar view of the OMESFET illustrated in FIG. 5;

FIG. 7 is a planar topology of a pixel comprised of three pairs of red,green and blue (RGB) emitting OMESFET's;

FIG. 8 is a cross section of the preferred complementary OMESFET logicdevice;

FIG. 9 is a conceptual, planar diagram of an ink-jet printing systemfilling polymer semiconductor areas in pattern and sequence to form anEL device; and

FIG. 10 is a partial cross section showing interconnected pixel elementsshown in FIG. 3 and the OMESFET logic device shown in FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

The invention discloses electroluminescent and photonic devices withimproved efficiency and operation. The devices are designed forefficient and cost effective fabrication using solution deposition andink-jet printing methodology. Alternately the devices can be woven fromappropriate materials as disclosed in U.S. patent application Ser. No.09/218,233.

Interface low mobility, contact barrier, space charge limitation andcarrier balancing are incorporated in the improved devices. Theseproperties tend to increase efficiency, increase reliability andlongevity, reduce a power loss, and reduce power requirement of LEDdevices. The use of true-ohmic contact materials in a light emittingtriode OMESFET configuration is disclosed. This contact material in thedisclosed configuration eliminates ITO commonly used in prior artdevices.

This increases luminous output, and provides ease of address and controlby the use of integrally fabricated triode address and controlcircuitry.

The above cited references, which are entered into this disclosure byreference, teach the principles, materials and means for providing truesolid/solid interface Mott-Gurney, no barrier, true-ohmic contact ton-type semiconducting inorganic and metal-organic compounds, polymersand copolymers of band gaps greater than 2 eV. These contacts areembodied in electronic circuitry, EL and other photonic devices. Againsummarizing, the references teach that a contact made between an n-typesemiconductor and a conductor whose work function is less than thesemiconductor band gap, charge exchange occurs to obtain a state ofequilibrium. In the charge exchange process, interface traps are filledand the conduction band of the semiconductor is accumulated withelectrons. The greater the difference between the band gap and the workfunction, the greater the exchange to achieve equilibrium therebyfilling some bulk traps as well. The net effect is to increaseconductivity and electron mobility of the device. These basic principlesare applied to the present disclosure.

Two high conductivity contacting metals, each capable of producing trueohmic contact to semiconductors and EL semiconductors of band gapgreater than 2 eV, are employed in the present invention. These contactmaterials are CuCa₂ with a work function of about 1.6 eV, and Al₂Li₃with a work function of about 1 eV. CuCa₂ adapts readily into the priorart LED processing environment, requiring background pressure of 10⁻⁶mbar of O₂. As mentioned previously, printing and other solutiondeposition processes of Al₂Li₃ requires a suitably positive pressure ofargon (Ar) both during the solution formation and the deposition.Polymers and co-polymers of electroluminescent devices and both CuCa₂and Al₂Li₃ require protective coating, or overall encapsulation, toprevent oxidation. Either CuCa₂ contacts, or preferably Al₂Li₃ contactsimprove LED operation. SiO₂ pacifies Al₂Li₃.

Prior art LEDs are contact barrier controlled and operate by tunnelingof carriers. In the present invention, barriers are eliminated andradiative emission is reduced relative to prior art ITO cathode devicesby transforming a LED structure into a triode having structuralcharacteristics of an OMESFET including a surrounding Schottky gate thatcontrols carrier energy and balance. True-ohmic contacts are formed andinject carriers fill interface and bulk traps. This increases carriermobility by a factor approaching 10⁴ and space-charge distance by afactor of 40 or more, thereby allowing more concentration of radiativechain emission and thus more radiated output.

The pixel OMESFET embodiment operates in a short-channel, normally“off”, gate-controlled high-energy mode, up to and including avalanche,thereby increasing radiative output and decreasing power required.Details of MESFET operation is included in standard texts such as apublication by M. E. Sze, Physics of Semiconductor Devices, page 322.The OMESFET field has polymer-chain field orientation, rather than LEDcross-chain field, thereby further improving efficiency and radiativeemission by lowering non-radiative interchain reaction. The OMESFET'ssurrounding gate enhances carrier balancing.

An important feature of the invention is that carrier balancing may be“tuned” for a particular polymer or co-polymer by the positioning of thegate relative to the cathode. The OMESFET gate electrode providesreduced cross talk and ease of pixel addressing as compared to LED's.OMESFET pixel address and control circuitry are integrally fabricatedwith pixel arrays for efficiency and economy of fabricating displayproducts

Description of the Devices

Attention is first directed to FIG. 1 which is a partial section view ofthe prior art LED. The structure is generally denoted by the numeral 10.Starting at the bottom of the illustration, an organic EL material 14contacts an ITO hole injection barrier contact 12. A low electronbarrier contact is identified at 15 and may be Al, Ca, Mg orcombinations thereof as reviewed by Friend. The resulting barrier isabout 0.2 eV. Components 14 and 15 are encapsulated with a polymerencapsulating material 16. The prior art device is illustrated forbackground purposes only, and no claims are made regarding thisillustration of the prior art.

FIG. 2 illustrates a partial section of an improved LED. The structureis generally denoted by the numeral 20. The device 20 is an improvementover the prior art device in function as well as in fabrication.Regarding fabrication, the device 20 as embodied can be solutiondeposited or “printed”, as opposed to prior art deposition and etchingmethods. These techniques significantly reduce fabrication costs. As anexample, an improvement is embodied by first printing or otherwisedepositing organic electroluminescent material 14 upon a contact 12,followed by an overlay printing of a true-ohmic contact metal 18, andfinally by an overlay printing of an interconnect metal 17. Thetrue-ohmic contact metal 18 preferred is one having the largest ratio ofthe band gap of the EL material 14 to the work function of the contactmetal. The preferred contact 18 is Al.sub.2Li.sub.3 of work function ofabout 1 eV. Solution forming and printing volatile Al.sub.2Li.sub.3requires the same oxygen free environment as for layer 14, plus asuitable positive pressure of Ar. An alternative embodiment for contact18 is to print CuCa.sub.2 of work function of about 1.6 eV, which doesnot require an Ar environment. Both contact metals result in thepreviously discusses device operation and performance specifications.The same oxygen free environment required for printing of the ELmaterial 14 is used to form solution and printing of CuCa.sub.2.Components 14, 17 and 18 are encapsulated with a polymer material 16 onthe contact 12, which is preferably a ITO hole injection contact 12.

Attention is next directed to FIG. 3 which is a partial section of theimproved EL device embodied as a OMESFET structure used in red, blue andgreen (R, B and G) pixels, and also used in pixel address and controlcircuitry. The OMESFET in an integral component of a video display,which is discussed in subsequent sections of this disclosure. TheOMESFET structure is generally denoted by the numeral 30. The device 30comprises a metal-organic or copolymer n-type EL semiconductor 33. Asource true-ohmic contact metal 32 contacts the source end of the ELsemiconductor 33, and a drain true-ohmic contact metal 37 contacts thedrain end of the EL semiconductor 33. A high work function surround gatemetal 35 contacts the EL semiconductor between the source contact metal32 and the drain contact metal 37. The gate 35 is preferably fabricatedfrom printed Au or other conductors and having a barrier to n-typesemiconductor 33 of 5 eV or more. Interconnect metals for source 32,drain 37 and gate 35 are denoted by 31, 36 and 34, respectively. Whenthe gate 35 is located equidistant from source 32 and drain 37, thedistances designated 38 and 39 are equal and about 3000 nanometers (nm)each. Some co-polymer semiconductors may require gate 35 to be closer tosource contact 32 for current balancing. In that instance, neither 38nor 39 should exceed 3000 nm, to eliminate space-charge currentlimitation. Current balancing can thereby be “tuned” by placement of thegate 35.

Still referring to FIG. 3, the OMESFET device 30 is operated normally inthe “off” mode. The source interconnect metal 31 is normally connectedto system ground potential, as shown at 71 in FIG. 7. Gate interconnectmetal 34 is operated at a negative potential relative to the source 31.That potential is supplied by address and control logic as discussed insubsequent sections of this disclosure. The drain interconnecting metal36 is operated at a positive potential relative to that of source 31 andgate interconnect 34. That potential is also supplied by address andcontrol logic device illustrated in FIG. 10.

Attention is next directed to FIG. 4, which is a partial planar view ofthe OMESFET shown in sectional view in FIG. 3. The structure is againdenoted by the numeral 30. The organic semiconductor 33 is shown boundedon the left with the true-ohmic contact metal 32 of the source, and onthe right by the true-ohmic contact metal 37 of the drain. The highbarrier surround gate conductor 35 is shown positioned on the organicsemiconductor 33 approximately midway between the true-ohmic contactmetals 32 and 37. The interconnect metals 31, 34 and 36 have beenomitted for clarity.

FIG. 5 shows a partial cross section of the EL device configured as anOMESFET and further configured for fabrication using solution depositionand printing techniques. This embodiment of the improved OMESFET isdenoted as a whole by the numeral 50. Organic semiconductor material isdeposited upon a substrate 51. True-ohmic contact metals 53 and 56 arenext deposited upon the organic semiconductor material 33 as elementssource and drain contacts, respectively. Preferably in the samefabrication step, a high barrier surface gate conductor 54 is depositedupon the organic semiconductor 33 at a distance 38 from the true-ohmiccontact metal 53 and a distance 39 from the true-ohmic contact metal 56.Finally, source interconnect metal 52, drain interconnect metal 55, andgate interconnect metal 34′ are deposited over the elements 53, 56 and54, respectively. The elements must be encapsulated to protect fromoxygen. This encapsulation is not shown for reasons of clarity.

FIG. 6 is a partial planar view of the OMESFET shown in sectional viewin FIG. 5. The structure is again denoted by the numeral 50. The organicsemiconductor 33 is shown bounded on the left with the true-ohmiccontact metal 53 of the source, and on the right by the true-ohmiccontact metal 56 of the drain. The high barrier surface gate conductor54 is shown positioned on the organic semiconductor 33 approximatelymidway between the true-ohmic contact metals 53 and 56. The interconnectmetals 53, 34′ and 55 have been omitted for clarity.

FIG. 7 is a planar view of a three pairs of red, green and blue (RGB)emitting EL OMESFETs configured as a pixel. Green luminous EL co-polymer74, blue luminous EL co-polymer 75, and red luminous EL co-polymer 76′are deposited upon a transparent substrate and oxygen barrier 79. Commonsource true-ohmic contact and interconnect metals are denoted by thenumeral 71. Gate electrodes for redundant green pixel elements, bluepixel elements and red pixel elements are identified as 72, 76 and 78,respectfully. Elements 77 and 77′ are inter EL co-polymer isolationdielectric elements. The pixel common drain and true-ohmic contact andinterconnect is shown at 73.

FIG. 8 is a cross section of a complementary OMESFET logic device 80.Such a device is suitable for controlling pixels in a video display aswill be illustrated subsequently. A logic output interconnect metal isshown at 88 contacting p-source ohmic contact metal 86 and n-drain ohmiccontact metal 89. Isolating dielectric 84 abuts opposing sides of thelogic output interconnect metal 88. Element 82 is an n-typesemiconductor with a high barrier surrounding gate 81. Element 83 is ap-type semiconductor with a high barrier surrounding gate 85. A n-sourceohmic contact metal 82′ and cooperating n-source interconnect metal 82″contact the n-type semiconductor 82. Likewise, a p-drain ohmic contactmetal 83′ and cooperating p-drain interconnect metal 83″ contact thep-type semiconductor 83. A gate metal 87 contacts the high barriersurrounding gates 85 and 81, the p-type semiconductor element 83, andthe n-type semiconductor element 82. The gate interconnect metal 87 isisolated from the p-drain interconnect metal 83″ and the n-sourceinterconnect metal 82″ by isolating dielectric material 84.

Fabrication by Printing

The devices of the present disclosure, and more specifically a colorvideo display device, can be fabricated by printing elements of thedevice upon a transparent substrate in patterns and in a sequencerequired to fabricate the device.

FIG. 9 is a conceptual, planar diagram of an ink-jet printing system 90filling polymer semiconductor areas in pattern and sequence to form anEL device. An ink jet 91 is supplied with appropriate materials forprinting a device from a plurality of reservoirs 98, 98′ and 98″. Itshould be understood that additional or fewer reservoirs can beemployed. Material is fed to the ink jet printer in quantity and typeunder the control of a central processor unit (CPU) 95, which ispreprogrammed to fabricate a specific device. The ink jet 91 moves alonga path 91′ back and forth across an area 97 of semiconductor materialdepositing or “writing” appropriate components until the desired patternand width is completed. Movement is controlled by the CPU 95 which ispreprogrammed to fabricate a specific type of device. Printing iscarried out under a controlled atmosphere until the device isencapsulated for protection.

FIG. 9 illustrates, as an example, the ink-jet system 90 fabricating aparticular portion of a specific device. The example device will have apotential between source 92 and drain 93, and a field therebetweencontrolled by gate 94. The object of ink-jet printing illustrated is toprovide polymer chains parallel to the field applied to the devicethereby increasing radiative emission, and reducing cross-chain carriermovement that seldom contributed to such emission.

It should be emphasized that fabrication of the devices discussed aboveby material deposition is not limited to ink jet printing. Other meansof material deposition may be used such as stamping particular elementsin particular patterns. Furthermore, combinations of material depositionmay be effectively employed. As an example, a surface of organicsemiconducting material can be fabricated by a number of means, andsubsequent elements of the device can be deposited upon thesemiconductor by ink-jet printing, or by stamping, or by other suitablemethods.

Fabrication by Weaving

The devices of the present disclosure, and more specifically a colorvideo display device, can alternately be fabricated by weaving orknitting particular inorganic and organic materials that are formed intofibers. This process is described in more detail in previously enteredreference U.S. patent application Ser. No. 09/218,233. Polymer fibers,preferably in the form of thread, are used for EL, and dielectricisolation. Metals or cermets, preferably in the form of thread, are usedfor interconnection conductive polymer. Constituent fiber dimensionsdetermine the size of the display device. Fiber width of all materialsof the display can vary from sub-micron to millimeter dimensions. Sizeof the overall display is limited by the tensile strength of interwovendielectric fibers. These fibers bear the stress of the looming of thedisplay fabric, and are allowed to stretch as long as functionalintegrity is maintained. In weaving, “woof” refers to threads woven backand forth across fixed threads of the “warp” in a loom. In the contextof the present disclosure, the length at which fiber strength fails andat which the fiber breaks determines the maximum dimension of warp andwoof of the weaving loom. Pixel density of the display is proportionalto the EL polymer fiber width, where the least display area has thehighest pixel density. For a constant pixel density as display areaincreases, the thickness of the insulating fibers are increased towithstand the increased warp and woof tensions of the loom, therebyincreasing the overall thickness of the display panel. The resultingfabric display has an overall area, or number of displays of a wovenbatch, limited only by the weaving loom's capability and the breakingpoint of the insulating fibers used. A full color flat-panel display canbe as thin, front-to-back including encapsulation, of less than one-halfinch. The display retains operational performance with mechanicalflexing.

Integrated Logic Device

FIG. 10 is a partial cross section showing an integrated logic EL device100 comprising the pixel element shown in FIG. 3 and the OMESFET logicdevice shown in FIG. 8. Material 184 is isolating dielectric material,which surrounds many elements of the device. Contacts 132, 135 and 137are source, gate and drain contacts, respectfully, interfacing anorganic semiconductor material 133. Logic output interconnect metal 188contains p-source ohmic contact metal 186 and n-drain contact metal 189.The elements 183 and 182 are p-type semiconductor material and n-typesemiconductor material, respectively. High barrier surround gates 185and 181 contact the elements 183 and 182, respectfully. The elements183′ and 182′ are p-drain ohmic contact metal and n-source ohmic contactmetal, respectfully, and 183″ and 182″ are p-drain and n-sourceinterconnect metals, respectfully. Gate interconnect metal 187 connectsthe high barrier surrounding gates 185 and 181. The entire device isencapsulated with a suitable material (not shown) to exclude oxygen.

Several complementary OMESFETs are required to accomplish any givenlogic and control functions and can be integrally fabricated in layersabove and connected to gate, source and drain terminals 34, 31 and 36,respectfully, shown in FIG. 3.

While the foregoing disclosure is directed to embodiments of the presentinvention, other and further embodiments of the invention may be devisedwithout departing from the basic scope thereof is determined by theclaims that follow.

1. A method for fabricating an EL device, said method comprising:storing one or more constituent materials of the EL device in a solutionform, wherein the constituent materials comprise a true-ohmic contactmetal; and printing the constituent materials in patterns and in asequence on a substrate to form at least a portion of the EL device,wherein the printing is done in a substantially oxygen free environment.2. The method of claim 1, wherein the printing is implemented with anink jet that moves along a predefined path that goes back and forthacross a predetermined area.
 3. The method of claim 1, furthercomprising encapsulating the EL device after printing the constituentmaterials to protect the constituent materials from oxidation.
 4. Themethod of claim 1, further comprising applying a protective coating tothe constituent materials after printing to prevent oxidation.
 5. Amethod to fabricate an EL display with integrally fabricated logicdevices, said method comprising: depositing solution forms of at leastEL semiconductor materials, ohmic contact metals, and gate conductormaterials in a first pattern and sequence on a transparent substrate toform EL pixel elements configured for emitting light; and depositingsolution forms of at least p-type semiconductor materials, n-typesemiconductor materials, ohmic contact metals, and gate conductormaterials in a second pattern and sequence on top of the EL pixelelements to form complementary logic devices with respective outputsthat control the EL pixel elements.
 6. The method of claim 5, whereineach of the EL pixel elements has an OMESFET structure comprising astrip of EL semiconductor material, a first true-ohmic contact metalcontacting the strip of EL semiconductor material at one end to define asource terminal, a second true-ohmic contact metal contacting the stripat EL semiconductor material at another end to define a drain terminal,and a surround gate or a surface gate contacting the strip of ELsemiconductor material between the source terminal and the drainterminal to define a gate terminal.
 7. The method of claim 6, whereinthe gate terminal, the source terminal, or the drain terminal the ELpixel element is connected to the output of the complementary logicdevice above the EL pixel element.
 8. The method of claim 5, furthercomprising encapsulating the EL pixel elements and the complementarylogic devices after solution deposition to prevent oxidation.
 9. Themethod of claim 6, wherein the surround gate or the surface gate ispositioned approximately midway between the source terminal and thedrain terminal.
 10. The method of claim 6, wherein the surround gate orthe surface gate is separated from the source terminal or the drainterminal by no more than about 3000 nanometers.
 11. The method of claim6, wherein the surround gate or the surface gate is positioned closer toeither the source terminal or the drain terminal.
 12. The method ofclaim 5, wherein the EL semiconductor materials comprise an n-typemetal-organic semiconductor.
 13. The method of claim 5, wherein theohmic contact metals comprise CuCa₂ or Al₂Li₃.
 14. The method of claim5, wherein the gate conductor materials comprise gold.
 15. The method ofclaim 5, wherein the gate conductor materials have a relatively highwork function with respect to the EL semiconductor materials.
 16. Themethod of claim 5, wherein the solutions are deposited by stamping or byprinting techniques of an ink-jet system.
 17. The method of claim 5,wherein the solutions are deposited in a substantially oxygen freeenvironment.
 18. The method of claim 1, wherein the constituentmaterials further comprise an EL material and a gate conductor materialprinted on the substrate such that the EL material has a first surfacethat contacts the substrate and a second surface that contacts thetrue-ohmic contact metal and the gate conductor material.
 19. The methodof claim 18, wherein the EL material comprises an n-type metal-organicsemiconductor.
 20. The method of claim 18, wherein the gate conductormaterial comprises gold.
 21. The method of claim 18, wherein a strip ofgate conductor material is printed between two strips of true-ohmiccontact metal on top of the EL material to form an OMESFET structure.22. The method of claim 21, wherein the gate conductor material isseparated from the strips of true-ohmic contact metal by no more than3000 nanometers.
 23. The method of claim 1, wherein the true-ohmiccontact metal comprises CuCa₂ or Al₂Li₃.
 24. The method of claim 1,wherein the substrate is an optically transparent material.
 25. Themethod of claim 1, wherein the EL device is configured as a videodisplay.
 26. The method of claim 1, wherein the constituent materialsare stored in a plurality of reservoirs and an ink jet system prints theconstituent materials on the substrate.